There has been considerable research to date directed toward developing compositions that can retain (within and/or on) and subsequently release matter of interest. For example, drug release compositions form an important role in the medical industry. Such compositions include those where a drug is blended with polymer to form a drug/polymer composite. The polymer/drug composites may then be used as a drug release medium. For example, silicone rods comprising levonorgestrel have been used as a slow release birth control implant.
Despite release of drugs from such media being reasonably effective, there can be problems associated with the fate of a given medium after the drug has been released. For example, in the case of the levonorgestrel implant, after release of the drug the “spent” implant must be surgically removed from the subject. During removal several incisions may be required and/or the implant can fragment upon being withdrawn.
Other types of media have been developed for use in cell culture. Cell culture is typically carried out by seeding a suitable medium with cells that are to be cultured. Certain cell types, such as human embryonic stem cells (hESC) and induced pluripotent cells (iPC's), are more effectively cultured by providing a surface upon which the cells can adhere and proliferate. After adhesion and proliferation, the cultured cells need to be harvested and therefore released from the surface. Release of the cells is typically promoted by techniques such as mechanical scraping, sonication, chemical or enzymatic treatment, or a combination thereof.
Common cell release techniques can present a number of problems. For example, mechanical scraping can damage the cells, and it is often not suitable for use in confined spaces such as small diameter wells or with three dimensional structures. The use of chemical or biological agents to facilitate release of cultured cells from a given substrate can also damage the cells and/or present a risk of introducing impurities into the cultured cells. For example, a common agent such as trypsin is known to promote deterioration of cell function. Furthermore, certain cells can be particularly adherent to a given substrate and need to be subjected to forcing conditions to promote their release, the effect of which inevitably results in a degree of cell damage.
Conventional release media used in cell culture also often lack versatility in that a given medium, such as a substrate suitable for cell culture, will often not be a suitable medium for use in other applications such as drug release.
An opportunity therefore remains to develop more versatile release media that can be used in a variety of applications and/or address at least some of the problems associated with the release of matter, such as cells or drugs, from the media.